i have a Ti fork. my king crown race fits a little loose on it. barnetts also recommends gnurling and/or using loctite 680 retaining compound, but does not address whether gnurling or the loctite is compatible with Ti! i dont want to ruin the tool attempting to gnurl it.
I'm no expert, but used to collect bike mag articles that dealt with alternative materials. Titanium's considered the "hot-rod" of metals. I recall a clip that stated the bits they use to machine steel tubes would do 30 steel tubes but only three titanium tubes before needing resharpening. That figure sticks in my mind - I take it that titanium is harder (though lighter) than steel. I hope that helps.
The reason drill-bits and cutting tools wear out faster on ti is because its thermal conductivity is only 1/2 that of steel. So the surface temperature at the contact area heats up a lot more than steel. This heat wears out cutting tools faster.
Rockwell (surface) hardness of ti is about 1/10th to 1/5th that of steel. Modulus (stiffness) of ti is also about half that of steel. However, strength (yield & ultimate) can be twice that of steel, so you've got a soft springy material. Knurling tools will work just fine on ti, you'll need to run it through twice because the material springs back and doesn't take a set as easily as steel.